Materials Science and Engineering, University of Texas at Austin, Austin, Texas 78712, United States.
International Iberian Nanotechnology Laboratory, 4715-330 Braga, Portugal.
Nano Lett. 2023 Mar 8;23(5):1858-1864. doi: 10.1021/acs.nanolett.2c04764. Epub 2023 Feb 27.
The evolution of Pt nanoparticles in proton-exchanged membrane fuel cells is monitored before and after electrochemical potential cycling, using 2D and 3D identical location aberration-corrected transmission electron microscopy. This work demonstrates that 2D images might be a challenge to interpret due to the 3D nature of the carbon support. Thus, it is critical to combine both 2D and 3D observations to be able to fully understand the mechanisms associated with the durability of Pt catalyst nanoparticles. In particular, this investigation reveals that the mechanism of particle migration followed by coalescence is operative mainly across short distances (<0.5 nm). This work also shows that new Pt particles appear on the carbon support, as the result of Pt dissolution, followed by the formation of clusters, which grow by Ostwald ripening. This mechanism of Ostwald ripening is also responsible for changes in shape and particle growth, which later may result in coalescence.
使用二维（2D）和三维（3D）相同位置的像差校正透射电子显微镜，在电化学电势循环前后监测质子交换膜燃料电池中 Pt 纳米颗粒的演变。这项工作表明，由于碳载体的 3D 性质，2D 图像可能难以解释。因此，结合 2D 和 3D 观察结果对于能够充分理解与 Pt 催化剂纳米颗粒耐久性相关的机制至关重要。特别是，这项研究表明，颗粒迁移随后发生聚结的机制主要在短距离内（<0.5nm）起作用。这项工作还表明，由于 Pt 的溶解，新的 Pt 颗粒出现在碳载体上，随后形成簇，通过奥斯特瓦尔德熟化生长。这种奥斯特瓦尔德熟化机制也导致了形状变化和颗粒生长，这可能导致后来的聚结。
